617 
FXUS65 KTWC 080923
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
223 AM MST Fri Oct 8 2021

.SYNOPSIS...Dry and warm weather is expected through the weekend, with
periods of passing high clouds and afternoon breezes. A stronger 
and colder system will move into the region early next week. This 
system may result in windy conditions, colder temperatures, and a
chance of showers across portions of southeast Arizona.

&&

.DISCUSSION...Water vapor imagery shows high pressure to our
southeast with the center of the high over northern Mexico. A
trough is beginning to move into the western U.S. High clouds are
moving through thanks to southwest flow out ahead of the trough.
Expect this cloudiness to stick around today with temperatures
similar to yesterday. 

Saturday into Sunday morning the trough will move through Arizona
with its center over southern Utah and northern Arizona. Moisture
will be in short supply so not expecting any precipitation as the
low moves through. However this trough will tighten the surface 
pressure gradient leading to breezy winds Saturday afternoon, 
especially in Cochise County. A cooler air mass will also be 
moving in leading to temperatures 4-6 degrees below normal 
Saturday and 7-10 degrees below normal Sunday. 

Next week the pattern stays progressive with brief weak ridging
Monday before another trough moves into the West. Ensembles show
this upper level low start to move through Monday night then
deepen as it moves through Arizona Tuesday. There is still some 
disagreement in the speed it moves through, but good agreement 
that it will be an anomalously deep low for this time of year. At
the surface this will translate into temperatures 12-18 degrees 
below normal Tuesday and Wednesday along with strong gusty winds 
Monday and Tuesday afternoons. The first freeze of the year will 
be possible for the Sulphur Springs Valley Wednesday and Thursday 
mornings. Wednesday morning looks to have the best chance with the
NBM giving the Sulphur Springs Valley a 45-55 percent chance of 
hitting 32 degrees or lower. Areas between Sonoita and Patagonia 
also have between a 30-40 percent chance of seeing freezing 
temperatures Wednesday morning. Tucson low temperatures will be in
the low to mid 40s. Precip chances also return Tuesday mainly 
northeast of Tucson. Mountain snow mainly above 7000 feet will be 
possible, but at this time it looks like any rain or snow 
accumulations will be fairly light.

After Wednesday temperatures will follow a warming trend but will
still be below normal. 

&&

.AVIATION...Valid through 09/12Z.
Expect SCT-BKN clouds AOA 25k ft MSL through much of today then 
becoming SKC or a FEW clouds AOA 25k ft this evening onward. Light 
SFC winds except becoming WLY 7-12 kts with gusts to 20 kts during 
the afternoon hours. Aviation not updated for TAF amendments. 

&&

.FIRE WEATHER...
Dry and warm weather is expected through the weekend with periods of 
passing high clouds and afternoon breezes. Surface wind speeds will 
remain between 10-15 mph with intermittent gusts to around 20 mph 
each afternoon, favoring the west to southwest. Stronger winds along 
with much colder temps and a slight chance for rain are expected 
early next week as a stronger, colder weather system moves in. 20-ft 
winds will be southwesterly near 15-25 mph both Monday and 
especially Tuesday with higher gusts. RH values will remain above 
critical thresholds. 

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

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